We have noted that IV DMT elicits robusts elevations in blood levels of beta-endorphin compared to placebo. This rise in BE precedes a similarly robust increase in prolactin levels. We would like to determine the effects of blockading endogenous opiods using an infusion of naloxone beginning immediately before DMT administrtion, and continuing out to the end of the sampling period (+60 minutes). We will assess effects of opioid blockade on the subjective, opioid like effects of DMT as well as possible effects of BE on prolactin